Field
The present disclosure relates generally to systems for creating a durable seal between adjacent panels, including those which may be subject to temperature expansion and contraction or mechanical shear. More particularly, the present disclosure is directed to an expansion joint design for supporting transfer loads while permitting flexion of the associated structure.
Description of the Related Art
Construction panels come in many different sizes and shapes and may be used for various purposes, including roadways, sideways, and pre-cast structures, particularly buildings. Use of precast concrete panels for interior and exterior walls, ceilings and floors, for example, has become more prevalent. As precast panels are often aligned in generally abutting relationship, forming a lateral gap or joint between adjacent panels to allow for independent movement, such in response to ambient temperature variations within standard operating ranges, building settling or shrinkage and seismic activity. Moreover, these joints are subject to damage over time. Most damage is from vandalism, wear, environmental factors and when the joint movement is greater, the seal may become inflexible, fragile or experience adhesive or cohesive failure. As a result, “long lasting” in the industry refers to a joint likely to be usable for a period greater than the typical lifespan of five (5) years. Various seals have been created in the field.
Various seal systems and configurations have been developed for imposition between these panels to provide seals which provide one or more of fire protection, waterproofing, sound and air insulation. This typically is accomplished with a seal created by imposition of multiple constituents in the joint, such as silicone application, backer bars, and compressible foams.
Expansion joint system designs for situations requiring the support of transfer loads have often required the use of rigid extruded rubber or polymer glands. These systems lack the resiliency and seismic movement required in expansion joints. These systems have been further limited in functioning as a fire-resistant barrier, which is often a desired function.
Other systems have incorporated cover plates that span the joint itself, often anchored to the concrete or attached to the expansion joint material and which are expensive to supply and install. Additionally, cover plates that are higher than the deck or substrate level can present a hazard, such as tripping, an unnecessary impediment, such as to wheelchairs. Further, these systems require undesirable mechanical attachment, which requires drilling into the deck or joint substrate. Cover plate systems that are not mechanically attached rely on support or attachment to the expansion joint, thereby subject the expansion joint system to continuous compression, expansion and tension on the bond line when force is applied to the cover plate, which shortens the life of the joint system.
Further, other systems have been developed which use a resiliently compressible material, such as foam, cut into rectangular prisms, providing two flat opposing surfaces which can be adhered to the adjacent substrates and a flat top surface which, when compressed, pushes upward, such as in a single dome or in a series of smaller domes, which is sometimes characterized as a bellows.
It would be an improvement to provide a modified structure which includes external shaping to facilitate more rapid installation, to resist upward deflection, particularly during installation, and which contained internal voids to facilitate compression or for positioning of structural members.